Enhanced power headroom report for feeding back beamformed sounding reference source power scaling

ABSTRACT

Various aspects are described for an enhanced power headroom report (PHR) for feeding back beamformed sounding reference signal (SRS) power scaling. Beamformed SRS along directions where a user equipment (UE) can best nullify interference/maximize downlink (DL) signal to interference plus noise ratio (SINR) would be very helpful for DL beamforming. SRS beamforming requires additional support, if rank related decisions are being made at eNB. For example, power normalization factors need to be sent or reported on the uplink (UL) to eNB. This disclosure provides examples of how the PHR on the uplink can be used to do such reporting. There are two types of PHR being proposed, one nominal for the UL-oriented SRS, like LTE-style PHR, and one for the DL-oriented SRS where the UE also reports or indicates the power normalization factors of each SRS port.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of International Application No.PCT/CN2017/079358, entitled “ENHANCED POWER HEADROOM REPORT FOR FEEDINGBACK BEAMFORMED SRS POWER SCALING” and filed on Apr. 1, 2017, which isexpressly incorporated by reference herein in its entirety.

BACKGROUND

Aspects of the present disclosure relate generally to wirelesscommunication networks, and more particularly, to an enhanced powerheadroom report (PHR) for feeding back beamformed sounding referencesignal (SRS) power scaling.

Wireless communication networks are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing the available system resources (e.g., time, frequency, andpower). Examples of such multiple-access systems include code-divisionmultiple access (CDMA) systems, time-division multiple access (TDMA)systems, frequency-division multiple access (FDMA) systems, orthogonalfrequency-division multiple access (OFDMA) systems, and single-carrierfrequency division multiple access (SC-FDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. For example, a fifth generation (5G)wireless communications technology (which can be referred to as newradio (NR)) is envisaged to expand and support diverse usage scenariosand applications with respect to current mobile network generations. Inan aspect, 5G communications technology can include: enhanced mobilebroadband addressing human-centric use cases for access to multimediacontent, services and data; ultra-reliable-low latency communications(URLLC) with certain specifications for latency and reliability; andmassive machine type communications, which can allow a very large numberof connected devices and transmission of a relatively low volume ofnon-delay-sensitive information. As the demand for mobile broadbandaccess continues to increase, however, further improvements in NRcommunications technology and beyond may be desired.

For example, for NR communications technology and beyond, current SRSpower scaling reporting solutions may not provide a desired level ofspeed or customization for efficient operation. Thus, improvements inwireless communication operations may be desired.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. The sole purpose of thesummary is to present some concepts of one or more aspects in asimplified form as a prelude to the more detailed description that ispresented later.

Various aspects are described for an enhanced power headroom report(PHR) for feeding back beamformed sounding reference signal (SRS) powerscaling. Beamformed SRS along directions where a user equipment (UE) canbest nullify interference/maximize downlink (DL) signal to interferenceplus noise ratio (SINR) would be very helpful for DL beamforming. SRSbeamforming requires additional support, if rank related decisions arebeing made at a base station such as an evolved node B (eNB). Forexample, power normalization factors need to be sent or reported on theuplink (UL) to the base station. In this disclosure it is shown how thePHR on the uplink can be used to do such reporting.

There are two types of PHRs being proposed in the disclosure, one beinga nominal PHR (or Type 1 PHR) for a UL-centric SRS, like a Long TermEvolution-style (LTE-style) PHR, and one being a PHR (or Type 2 PHR) fora DL-centric SRS where the UE also reports the power normalization ofeach SRS port.

In an aspect, the present disclosure includes a method for wirelesscommunications generating, by a UE, a PHR including first powerinformation indicating a nominal power headroom value and second powerinformation indicating a desired transmit power for each of multiple SRSports of the UE, wherein the desired transmit power for one or more ofthe multiple SRS ports is different from a same transmit power used foran UL transmission on the multiple SRS ports; and transmitting, by theUE, the PHR to a base station.

In another aspect, the present disclosure includes a method for wirelesscommunications receiving, at a base station and from a UE, a PHRincluding first power information indicating a nominal power headroomvalue and second power information; and identifying, from the secondpower information, a desired transmit power for each of multiple SRSports of the UE, wherein the desired transmit power for one or more ofthe multiple SRS ports is different from a same transmit power used foran UL transmission on the multiple SRS ports.

Moreover, the present disclosure also includes apparatuses havingcomponents or configured to execute or means for executing theabove-described methods, and computer-readable mediums storing one ormore codes executable by a processor to perform the above-describedmethods.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 is a schematic diagram of a wireless communication networkincluding at least one user equipment (UE) and a base station accordingto this disclosure for an enhanced power headroom report (PHR) forfeeding back beamformed sounding reference signal (SRS) power scaling;

FIG. 2 is a schematic diagram of example components of the UE of FIG. 1;

FIG. 3 is a schematic diagram of example components of the base stationof FIG. 1;

FIG. 4 is a flow diagram of an example of a method for wirelesscommunications; and

FIG. 5 is a flow diagram of another example of a method for wirelesscommunications

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details. Additionally, the term“component” as used herein may be one of the parts that make up asystem, may be hardware, firmware, and/or software stored on acomputer-readable medium, and may be divided into other components.

The present disclosure generally relates to an enhanced power headroomreport (PHR) for feeding back beamformed sounding reference signal (SRS)power scaling.

Additional features of the present aspects are described in more detailbelow with respect to FIGS. 1-5.

It should be noted that the techniques described herein may be used forvarious wireless communication networks such as code-division multipleaccess (CDMA), time-division multiple access (TDMA), frequency-divisionmultiple access (FDMA), orthogonal frequency-division multiple access(OFDMA), single-carrier frequency-division multiple access (SC-FDMA)systems, and other systems. The terms “system” and “network” are oftenused interchangeably. A CDMA system may implement a radio technologysuch as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc.CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0and A are commonly referred to as CDMA2000 1×, 1×, etc. IS-856 (TIA-856)is commonly referred to as CDMA2000 1×EV-DO, High Rate Packet Data(HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants ofCDMA. A TDMA system may implement a radio technology such as GlobalSystem for Mobile Communications (GSM). An OFDMA system may implement aradio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA(E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal MobileTelecommunication System (UMTS). 3GPP Long Term Evolution (LTE) andLTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA,E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). CDMA2000and UMB are described in documents from an organization named “3rdGeneration Partnership Project 2” (3GPP2). The techniques describedherein may be used for the systems and radio technologies mentionedabove as well as other systems and radio technologies, includingcellular (e.g., LTE) communications over a shared radio frequencyspectrum band. The description below, however, describes an LTE/LTE-Asystem for purposes of example, and LTE terminology is used in much ofthe description below, although the techniques are applicable beyondLTE/LTE-A applications (e.g., to 5G networks or other next generationcommunication systems).

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in other examples.

Referring to FIG. 1, in accordance with various aspects of the presentdisclosure, an example wireless communication network 100 includes atleast one user equipment (UE) 110 with a modem 140 having a powerheadroom report (PHR) for sounding reference signal (SRS) component 150that provides an enhanced PHR for feeding back beamformed SRS powerscaling. The PHR for SRS component 150 can handle uplink-oriented SRSand downlink-oriented SRS resource types. Further, wirelesscommunication network 100 includes at least one base station 105 with amodem 160 having a PHR for SRS component 170 that receives and processesan enhanced PHR for feeding back beamformed SRS power scaling. The PHRfor SRS component 170 can handle uplink-oriented SRS anddownlink-oriented SRS resource types.

The wireless communication network 100 may include one or more basestations 105, one or more UEs 110, and a core network 115. The corenetwork 115 may provide user authentication, access authorization,tracking, internet protocol (IP) connectivity, and other access,routing, or mobility functions. The base stations 105 may interface withthe core network 115 through backhaul links 120 (e.g., S1, etc.). Thebase stations 105 may perform radio configuration and scheduling forcommunication with the UEs 110, or may operate under the control of abase station controller (not shown). In various examples, the basestations 105 may communicate, either directly or indirectly (e.g.,through core network 115), with one another over backhaul links 125(e.g., X1, etc.), which may be wired or wireless communication links.

The base stations 105 may wirelessly communicate with the UEs 110 viaone or more base station antennas. Each of the base stations 105 mayprovide communication coverage for a respective geographic coverage area130. In some examples, the base stations 105 may be referred to as abase transceiver station, a radio base station, an access point, anaccess node, a radio transceiver, a NodeB, eNodeB (eNB), gNB, HomeNodeB, a Home eNodeB, a relay, or some other suitable terminology. Thegeographic coverage area 130 for the base station 105 may be dividedinto sectors or cells making up only a portion of the coverage area (notshown). The wireless communication network 100 may include base stations105 of different types (e.g., macro base stations or small cell basestations, described below). Additionally, the plurality of base stations105 may operate according to different ones of a plurality ofcommunication technologies (e.g., 5G (New Radio or “NR”), fourthgeneration (4G)/Long Term Evolution (LTE), 3G, Wi-Fi, Bluetooth, etc.),and thus there may be overlapping geographic coverage areas 130 fordifferent communication technologies.

In some examples, the wireless communication network 100 may be orinclude one or any combination of communication technologies, includinga NR or 5G technology, an LTE or LTE-Advanced (LTE-A) or MuLTEfiretechnology, a Wi-Fi technology, a Bluetooth technology, or any otherlong or short range wireless communication technology. InLTE/LTE-A/MuLTEfire networks, the term evolved node B (eNB) may begenerally used to describe the base stations 105, while the term UE maybe generally used to describe the UEs 110. The wireless communicationnetwork 100 may be a heterogeneous technology network in which differenttypes of eNBs provide coverage for various geographical regions. Forexample, each eNB or base station 105 may provide communication coveragefor a macro cell, a small cell, or other types of cell. The term “cell”is a 3GPP term that can be used to describe a base station, a carrier orcomponent carrier associated with a base station, or a coverage area(e.g., sector, etc.) of a carrier or base station, depending on context.

A macro cell may generally cover a relatively large geographic area(e.g., several kilometers in radius) and may allow unrestricted accessby UEs 110 with service subscriptions with the network provider.

A small cell may include a relative lower transmit-powered base station,as compared with a macro cell, that may operate in the same or differentfrequency bands (e.g., licensed, unlicensed, etc.) as macro cells. Smallcells may include pico cells, femto cells, and micro cells according tovarious examples. A pico cell, for example, may cover a small geographicarea and may allow unrestricted access by UEs 110 with servicesubscriptions with the network provider. A femto cell may also cover asmall geographic area (e.g., a home) and may provide restricted accessand/or unrestricted access by UEs 110 having an association with thefemto cell (e.g., in the restricted access case, UEs 110 in a closedsubscriber group (CSG) of the base station 105, which may include UEs110 for users in the home, and the like). An eNB for a macro cell may bereferred to as a macro eNB. An eNB for a small cell may be referred toas a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB maysupport one or multiple (e.g., two, three, four, and the like) cells(e.g., component carriers).

The communication networks that may accommodate some of the variousdisclosed examples may be packet-based networks that operate accordingto a layered protocol stack and data in the user plane may be based onthe IP. A user plane protocol stack (e.g., packet data convergenceprotocol (PDCP), radio link control (RLC), medium access control (MAC),etc.), may perform packet segmentation and reassembly to communicateover logical channels. For example, a MAC layer may perform priorityhandling and multiplexing of logical channels into transport channels.The MAC layer may also use hybrid automatic repeat/request (HARQ) toprovide retransmission at the MAC layer to improve link efficiency. Inthe control plane, radio resource control (RRC) protocol layer mayprovide establishment, configuration, and maintenance of an RRCconnection between a UE 110 and the base stations 105. The RRC protocollayer may also be used for core network 115 support of radio bearers forthe user plane data. At the physical (PHY) layer, the transport channelsmay be mapped to physical channels.

The UEs 110 may be dispersed throughout the wireless communicationnetwork 100, and each UE 110 may be stationary or mobile. A UE 110 mayalso include or be referred to by those skilled in the art as a mobilestation, a subscriber station, a mobile unit, a subscriber unit, awireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology. A UE 110 may be a cellular phone, asmart phone, a personal digital assistant (PDA), a wireless modem, awireless communication device, a handheld device, a tablet computer, alaptop computer, a cordless phone, a smart watch, a wireless local loop(WLL) station, an entertainment device, a vehicular component, acustomer premises equipment (CPE), or any device capable ofcommunicating in wireless communication network 100. Additionally, a UE110 may be Internet of Things (IoT) and/or machine-to-machine (M2M) typeof device, e.g., a low power, low data rate (relative to a wirelessphone, for example) type of device, that may in some aspects communicateinfrequently with wireless communication network 100 or other UEs. A UE110 may be able to communicate with various types of base stations 105and network equipment including macro eNBs, small cell eNBs, macro eNBs,small cell eNBs, relay base stations, and the like.

A UE 110 may be configured to establish one or more wirelesscommunication links 135 with one or more base stations 105. The wirelesscommunication links 135 shown in wireless communication network 100 maycarry uplink (UL) transmissions from a UE 110 to a base station 105, ordownlink (DL) transmissions, from a base station 105 to a UE 110. The DLtransmissions may also be called forward link transmissions while the ULtransmissions may also be called reverse link transmissions. Eachwireless communication link 135 may include one or more carriers, whereeach carrier may be a signal made up of multiple sub-carriers (e.g.,waveform signals of different frequencies) modulated according to thevarious radio technologies described above. Each modulated signal may besent on a different sub-carrier and may carry control information (e.g.,reference signals, control channels, etc.), overhead information, userdata, etc. In an aspect, the wireless communication links 135 maytransmit bidirectional communications using frequency division duplex(FDD) (e.g., using paired spectrum resources) or time division duplex(TDD) operation (e.g., using unpaired spectrum resources). Framestructures may be defined for FDD (e.g., frame structure type 1) and TDD(e.g., frame structure type 2). Moreover, in some aspects, the wirelesscommunication links 135 may represent one or more broadcast channels.

In some aspects of the wireless communication network 100, base stations105 or UEs 110 may include multiple antennas for employing antennadiversity schemes to improve communication quality and reliabilitybetween base stations 105 and UEs 110. Additionally or alternatively,base stations 105 or UEs 110 may employ multiple input multiple output(MIMO) techniques that may take advantage of multi-path environments totransmit multiple spatial layers carrying the same or different codeddata.

The wireless communication network 100 may support operation on multiplecells or carriers, a feature which may be referred to as carrieraggregation (CA) or multi-carrier operation. A carrier may also bereferred to as a component carrier (CC), a layer, a channel, etc. Theterms “carrier,” “component carrier,” “cell,” and “channel” may be usedinterchangeably herein. A UE 110 may be configured with multipledownlink CCs and one or more uplink CCs for CA. CA may be used with bothFDD and TDD component carriers. The base stations 105 and the UEs 110may use spectrum up to Y MHz (e.g., Y=5, 10, 15, or 20 MHz) bandwidthper carrier allocated in a carrier aggregation of up to a total of YxMHz (x=number of component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or less carriers may be allocated for DL than for UL). TheCCs may include a primary CC and one or more secondary CCs. A primary CCmay be referred to as a primary cell (PCell) and a secondary CC may bereferred to as a secondary cell (SCell).

The wireless communications network 100 may further include basestations 105 operating according to Wi-Fi technology, e.g., Wi-Fi accesspoints, in communication with UEs 110 operating according to Wi-Fitechnology, e.g., Wi-Fi stations (STAs) via communication links in anunlicensed frequency spectrum (e.g., 5 GHz). When communicating in anunlicensed frequency spectrum, the STAs and AP may perform a clearchannel assessment (CCA) or listen before talk (LBT) procedure prior tocommunicating in order to determine whether the channel is available.

Additionally, one or more of the base stations 105 and/or the UEs 110may operate according to a NR or 5G technology referred to as millimeterwave (mmW or mmwave) technology. For example, the mmW technologyincludes transmissions in mmW frequencies and/or near mmW frequencies.Extremely high frequency (EHF) is part of the radio frequency (RF) inthe electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and awavelength between 1 millimeter and 10 millimeters. Radio waves in thisband may be referred to as a millimeter wave. Near mmW may extend downto a frequency of 3 GHz with a wavelength of 100 millimeters. Forexample, the super high frequency (SHF) band extends between 3 GHz and30 GHz, and may also be referred to as centimeter wave. Communicationsusing the mmW and/or near mmW radio frequency band has extremely highpath loss and a short range. As such, the base stations 105 and/or theUEs 110 operating according to the mmW technology may utilizebeamforming in their transmissions to compensate for the extremely highpath loss and short range.

The SRS can be used in a radio technology, such as LTE or NR, to soundthe UL channel. Reference signals are transmitted by the UE 110 so thatthe base station 105 can determine characteristics of the UL channel.SRS may also be used for DL purposes. That is, the UE 110 transmitsreference signals in the UL, but because there is reciprocity, the basestation 105 learns about the UL channel and uses that knowledge tobeamform on the DL channel by assuming that the channel is reciprocal.

In addition, the UE 110 may want to beamform the SRS to provideinformation as to the interference the UE 110 experiences but there mayneed to be some form of feedback mechanism to convey the desired actionsof the UE 110 to the base station 105. One aspect that is proposed aspart of this disclosure is to include the information as to theinterference the UE 110 experiences using power control mechanisms. Inconnection with the wireless communication network 100 in FIG. 1, andfor an enhanced PHR for feeding back the beamformed SRS power scaling,aspects of power control for SRS are described below.

The SRS transmit power follows that of the physical uplink sharedchannel (PUSCH), compensating for the exact bandwidth of the SRStransmission and with an additional power offset:

P_(SRS) _(offset)

Calculated power of SRS is given by the following expression:

P _(SRS calculated) =P _(SRSoffset)+10 log(M _(SRS))+P _(O) _(PUSCH) +αP_(L) +f

where

-   P_(SRS) _(offset) =the power offset of the SRS transmission over the    PUSCH power target (P_(O) _(PUSCH) );-   M_(SRS)=the number of physical resource blocks (PRBs) sounding of    PUSCH;-   P_(O) _(PUSCH) =a user-specific PUSCH power target;-   P_(L)=the estimated path loss (the UE 110 estimates the path loss    based on the DL RS); and-   f=a function used for closed-loop power control.-   and where the number of PRBs correspond to a bandwidth of    transmission.

Calculated power of PUSCH is given by the following expression:

P _(PUSCH calculated)=10 log(M _(PUSCH))+P _(O) _(PUSCH) +αP _(L)+Δ_(TF)+f

where

-   ∝=is the path loss compensation factor. In an example, a can be any    one of {0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1}. The specified value of    ∝ may come from a higher layer (e.g, SIB2) and may control some    back-off on the path loss to be used for the power of PUSCH;-   M_(PUSCH)=is the number of RBs allocated to the UE for PUSCH; and-   Δ_(TF)=is the modulation and coding scheme (MCS)-dependent    parameter.

Actual power for SRS is given by the following expression:

P _(SRS)=min{P _(CMax) , P _(SRS calculated)}

where

-   P_(CMax)=the maximum transmit power.

In connection with the PHR, the power headroom indicates how muchtransmission power is left for the UE 110 to use in addition to thepower being used by a current transmission. The power headroom isgenerally obtained as Power Headroom=UE Max TransmissionPower−calculated PUSCH Power. That is, the power headroom or PH isobtained by the following expression:

PH=P _(CMax) −P _(SRS calculated)

In some radio technologies, such as LTE, the PHR is a type of MACcontrol element (CE) that reports the headroom between the current UEtransmit (Tx) power (e.g., calculated power) and the maximum power.

The base station 105, e.g., eNodeB or eNB, can use the report value toestimate how much UL bandwidth the UE 110 can use for a specific slot.In one example, a report may use 64 levels with around 1 dB ranging from[−23, −22, . . . , 40, >40]. In some radio technologies, such as LTE andNR, there may be different triggers for the PHR. One trigger may be todetect or determine that a path loss change is greater than a certainthreshold. For example, the UE 110 may calculate the path loss based ona reference signal (RS) power notified by the base station 105 and themeasured RS power at an antenna port of the UE 110. If the report valuechanges over a certain threshold, the UE 110 may transmit the PHR to thebase station 105. Another possible trigger may be based on the use of aperiodic timer. For example, the UE 110 may transmit the PHR to the basestation 105 at after predetermined amount of time (e.g., 100 ms).

In an aspect of this disclosure, the signaling and formatting used forthe PHR can be also be used to convey information to the base station105 in addition to any beamforming that may be performed by the UE 110in connection with SRS transmissions.

There may be different SRS resource types. A first resource type may bean DL-oriented or UL-centric SRS (similar to LTE), and a second resourcetype may be a DL-oriented or DL-centric SRS. In some implementations,the UL-centric SRS may also be referred to as codebook-based,non-codebook-based, or UL beam management SRS and may be used for ULMIMO and transmission of data purposes.

In some implementations, the DL-centric SRS may referred to as antennaswitching SRS. In an example, these resource types may be used by thebase station 105 to beamform on the DL and transmission of channelinformation (e.g., pre-coding matrix index (PMI), rank indicator (RI),etc.), and are the resource types for which the UE 110 is not expectedto receive from the base station 105.

For the DL-oriented SRS, SRS port numbering has one-to-one mapping tothe PUSCH port numbering. UL SRSs are intended to be used by the basestation 105 to support UL channel-dependent scheduling and linkadaption. Based on an UL SRS, the base station 105 may make thescheduling decision and provide the UE 110 information about theresources and the associated transmission settings. The UL-oriented SRSmay be used to help maximize the UL signal-to-noise ratio (SNR) or theUL signal-to-interference-plus-noise ratio (SINR).

The DL-oriented SRS is for DL link adaptation and channel-dependentscheduling. SRS beamforming has been considered in the past as asolution and SRS beamformed along directions where the UE 110 can bestnullify interference and/or maximize DL SNR or DL SINR. SRS beamformingrequires additional support, if/when rank related decisions are beingmade at the base station 105. Accordingly, power or scalingnormalization factors may need to be sent on the UL channel to the basestation 105. This disclosure describes aspects of how information aboutthese normalizations factors can be sent to the base station 105 usingthe PHR signaling mechanisms. That is, the PHR can be used by the basestation 105 to recover information associated with the normalizationfactors that cannot be obtained solely from the beamforming performed bythe UE 110.

Regarding the power or scaling normalization factors, these factors candepend on a noise covariance interference matrix that the UE 110observes on the DL channel. For example, the UE 110 can measureinterference over each of n antennas of the UE 110, and can generate an×n channel covariance matrix representing interference over the nantennas. The UE 110 can determine a beamforming matrix based on thechannel covariance matrix for transmitting a beamformed reference signalsuch as beamformed SRS. The UE 110 can also normalize power for thebeamformed RS based on applying a normalization method to thebeamforming matrix. The UE 110 can accordingly transmit the beamformedRS to the base station 105 based on the normalized beamforming matrix.In accordance with this disclosure, the UE 110 may also transmitinformation about the power normalization factors to the base station105 by using an enhanced PHR. The base station 105 may accordinglydetermine interference conditions of the channel based on receiving thebeamformed RS, and using the power normalization factors associated withthe information provided by the enhanced PHR.

In an aspect, the present application describes an enhanced PHR thatenables the base station 105 to recover the “per-SRS-port” informationthat the UE 110 desired to use in order to transmit the SRS ports on theUL channel. However performing such transmissions could result in worseSRS channel estimation at the base station 105.

In an example, the base station 105 assumes that the UE 110 transmits onthe UL channel using the same power at each port. The UE 110, however,may want to use different power for each port to show which port (e.g.,beamformed direction) is stronger. The UE 110 transmits a PHR to thebase station 105, such that the base station 105 may estimate therelative difference in the power scaling that should have been applied.

In one example, assuming that the UE 110 has two SRS ports, and afterthe scaling normalization, the UE 110 wants to transmit with power P₁and P₂, in order to show that one of the ports has more interferencethan the other and the level of that interference. However, transmittingwith lower power per SRS port would result in lower channel estimation,which could possibly result in wrong channel estimation of that channel.Accordingly, the UE 110 transmits with equal or same power in each portto ensure that both ports have the same channel estimation quality.Then, the UE 110 needs to somehow report to the base station 105 howmuch was the actual power P₁ and P₂ that the UE 110 wanted to transmitbut did not use for transmission.

In a reporting example, the UE 110 may transmit three power headrooms(e.g., in separate reports), such that the eNB can recover thedifference of the two ports. In this example, the UE 110 may report:

PH⁽¹⁾ =P _(CMax) −P _(PUSCH calculated)

PH⁽²⁾ =P ₁

PH⁽³⁾ =P ₂

where the base station 105 can recover the P_(i) (i=1, 2) from PH(²) andPH⁽³⁾.

Note that the actual power headroom that the UE has is still the PH⁽¹⁾,because the UE did not actually apply the power difference in the ports.The PH⁽²⁾, PH⁽³⁾ is used just to notify the eNB the power difference ofthe port sounding that it should have been applied. The PH⁽²⁾, PH⁽³⁾ mayeven be per subband reported, so that the eNB can recover the P_(i) persubband. If the UE has X ports, then X additional numbers are needed tobe transmitted:

PH^((i+1)) =P _(i) for i=1, 2, 3, . . . X

In some aspects, the same format (e.g., an 8-bit format) to denote eachof the PHRs can be used for the additional PHRs.

The UE 110 may transmit three PHRs, such that the base station 105 canrecover the difference of the two ports. For example, the UE 110 mayreport:

PH⁽¹⁾ =P _(CMax) −P _(PUSCH calculated)

PH⁽²⁾ =P ₁

PH⁽³⁾ =P ₂−PH⁽²⁾

If the UE 110 has X number of ports, then X additional numbers of PHRsare needed to be transmitted:

PH⁽²⁾ =P ₁

PH^((i+1)) =P _(i)−PH^((i)) for i=2, 3, . . . X

Then, potentially fewer bits are needed (e.g., fewer than 8 bits) forthe additional PH^((i)) for i≥3.

The UE 110 can be configured with many SRS resources. For example, theUE 110 can be configured with multiple UL-oriented SRS resources,multiple DL-oriented SRS resources, or a combination of UL-oriented SRSresources and DL-oriented SRS resources. If the UE 110 was configuredand transmitted a DL-oriented SRS resource (even if other types of SRSresources are also configured), then a Type 2 PHR is used, where theType 2 PHR is a PHR that contains the power normalization factors (orinformation that conveys the power or scaling normalization factors).Even if the UE 110 has been configured with a DL-oriented SRS resource,it is likely the power normalizations factors may not need to betransmitted because the interference across ports is approximately thesame. Then, the UE 110 may use the Type 1 PHR.

In some implementations, if the UE 110 is only configured withUL-oriented SRS resources, then the Type 1 PHR can be used.

In some implementations, there can be one bit that is used to indicate aswitch between the Type 1 PHR and the Type 2 PHR.

In some implementations, the Type 2 PHR may be triggered whenever the UE110 transmits a DL-centric SRS resource and senses that any of the powernormalization scalings have significantly changed.

Referring to FIG. 2, one example of an implementation of UE 110 mayinclude a variety of components, some of which have already beendescribed above, but including components such as one or more processors212 and memory 216 and transceiver 202 in communication via one or morebuses 244, which may operate in conjunction with modem 140 and PHR forSRS component 150 to enable one or more of the functions describedherein that provides an enhanced PHR for feeding back beamformed SRSpower scaling. Further, the one or more processors 212, a modem 214, thememory 216, a transceiver 202, an RF front end 288, and one or moreantennas 286, may be configured to support voice and/or data calls(simultaneously or non-simultaneously) in one or more radio accesstechnologies.

In an aspect, the one or more processors 212 can include the modem 214that uses one or more modem processors. The various functions related tothe PHR for SRS component 150 may be included in the modem 140 and/orthe processors 212 and, in an aspect, can be executed by a singleprocessor, while in other aspects, different ones of the functions maybe executed by a combination of two or more different processors. Forexample, in an aspect, the one or more processors 212 may include anyone or any combination of a modem processor, or a baseband processor, ora digital signal processor, or a transmit processor, or a receiverprocessor, or a transceiver processor associated with the transceiver202. In other aspects, some of the features of the one or moreprocessors 212 and/or the modem 140 associated with the PHR for SRScomponent 150 may be performed by the transceiver 202.

Also, the memory 216 may be configured to store data used herein and/orlocal versions of applications 275 or the PHR for SRS component 150and/or one or more of its subcomponents being executed by at least oneof the one or more processors 212. The memory 216 can include any typeof computer-readable medium usable by a computer or at least one of theone or more processors 212, such as random access memory (RAM), readonly memory (ROM), tapes, magnetic discs, optical discs, volatilememory, non-volatile memory, and any combination thereof. In an aspect,for example, the memory 216 may be a non-transitory computer-readablestorage medium that stores one or more computer-executable codesdefining the PHR for SRS component 150 and/or one or more of itssubcomponents, and/or data associated therewith, when the UE 110 isoperating at least one of the one or more processors 212 to execute thePHR for SRS component 150 and/or one or more of its subcomponents.

The transceiver 202 may include at least one receiver 206 and at leastone transmitter 208. The receiver 206 may include hardware, firmware,and/or software code executable by a processor for receiving data, thecode comprising instructions and being stored in a memory (e.g.,computer-readable medium). The receiver 206 may be, for example, an RFreceiver. In an aspect, the receiver 206 may receive signals transmittedby at least one of the base stations 105. Additionally, the receiver 206may process such received signals, and also may obtain measurements ofthe signals, such as, but not limited to, energy-to-interference ratio(Ec/Io), SNR, reference signal received power (RSRP), received signalstrength indicator (RSSI), etc. The transmitter 208 may includehardware, firmware, and/or software code executable by a processor fortransmitting data, the code comprising instructions and being stored ina memory (e.g., computer-readable medium). A suitable example of thetransmitter 208 may including, but is not limited to, an RF transmitter.

Moreover, in an aspect, the UE 110 may include the RF front end 288,which may operate in communication with the one or more antennas 265 andthe transceiver 202 for receiving and transmitting radio transmissions,for example, wireless communications transmitted by at least one of thebase stations 105 or wireless transmissions transmitted by the UE 110.The RF front end 288 may be connected to the one or more antennas 265and can include one or more low-noise amplifiers (LNAs) 290, one or moreswitches 292, one or more power amplifiers (PAs) 298, and one or morefilters 296 for transmitting and receiving RF signals.

In an aspect, the LNA 290 can amplify a received signal at a desiredoutput level. In an aspect, each of the LNAs 290 may have a specifiedminimum and maximum gain values. In an aspect, the RF front end 288 mayuse the one or more switches 292 to select a particular LNA 290 and itsspecified gain value based on a desired gain value for a particularapplication.

Further, for example, the one or more PA(s) 298 may be used by the RFfront end 288 to amplify a signal for an RF output at a desired outputpower level. In an aspect, each of the one or more PA(s) 298 may havespecified minimum and maximum gain values. In an aspect, the RF frontend 288 may use the one or more switches 292 to select a particular PA298 and its specified gain value based on a desired gain value for aparticular application.

Also, for example, the one or more filters 296 can be used by the RFfront end 288 to filter a received signal to obtain an input RF signal.Similarly, in an aspect, for example, a respective filter 296 can beused to filter an output from a respective PA 298 to produce an outputsignal for transmission. In an aspect, each of the one or more filters296 can be connected to a specific LNA 290 and/or PA 298. In an aspect,the RF front end 288 can use the one or more switches 292 to select atransmit or receive path using a specified filter 296, LNA 290, and/orPA 298, based on a configuration as specified by the transceiver 202and/or the processor 212.

As such, the transceiver 202 may be configured to transmit and receivewireless signals through the one or more antennas 265 via the RF frontend 288. In an aspect, the transceiver 202 may be tuned to operate atspecified frequencies such that the UE 110 can communicate with, forexample, one or more of the base stations 105 or one or more cellsassociated with one or more of the base stations 105. In an aspect, forexample, the modem 140 can configure the transceiver 202 to operate at aspecified frequency and power level based on UE configuration of the UE110 and the communication protocol used by the modem 140.

In an aspect, the modem 140 can be a multiband-multimode modem, whichcan process digital data and communicate with the transceiver 202 suchthat the digital data is sent and received using the transceiver 202. Inan aspect, the modem 140 can be multiband and be configured to supportmultiple frequency bands for a specific communications protocol. In anaspect, the modem 140 can be multimode and be configured to supportmultiple operating networks and communications protocols. In an aspect,the modem 140 can control one or more components of the UE 110 (e.g., RFfront end 288, transceiver 202) to enable transmission and/or receptionof signals from the network based on a specified modem configuration. Inan aspect, the modem configuration can be based on the mode of the modemand the frequency band in use. In another aspect, the modemconfiguration can be based on UE configuration information associatedwith the UE 110 as provided by the network during cell selection and/orcell reselection.

The PHR for SRS component 150 can include multiple subcomponents. Forexample, the PHR for SRS component 150 can include a PHR generator 151that generates a PHR including first power information 152 and secondpower information 154. The first power information 152 includes anominal power headroom value 153, such as PH⁽¹⁾ as described above. Thesecond power information 154 includes additional power headroom values,such as PH⁽²⁾, . . . , PH^((X+1)), where X is the number of SRS ports inthe UE 110. The information in the second power information 154 (e.g.,the power headroom values) can indicate the desired transmit power 155for the SRS ports, which is different from the actual transmit power 156for the SRS ports. The desired transmit power 155 can be provided in theform of absolute transmit power values (e.g., P₁, . . . , Px) and/or inthe form of differential transmit power values (e.g., PH⁽²⁾=P₁ andPH^((i+1))=P_(i)−PH^((i)), for i=2, 3, . . . , X).

The PHR for SRS component 150 can also include a PHR type 157 thatidentifies or selects a type of the PHR from the Type 1 PHR and the Type2 PHR. The PHR type indication 158 can also be included in the PHR forSRS component 150 and can be used to provide an indication of the PHRtype.

Referring to FIG. 3, one example of an implementation of the basestation 105 may include a variety of components, some of which havealready been described above, but including components such as one ormore processors 312 and memory 316 and transceiver 302 in communicationvia one or more buses 344, which may operate in conjunction with themodem 160 and the PHR for SRS component 170 to enable one or more of thefunctions described herein related to receiving and processing anenhanced PHR for feeding back beamformed SRS power scaling. The basestation 105 may provide configuration information and/or otherinformation in response to the PHR.

The transceiver 302, receiver 306, transmitter 308, one or moreprocessors 312, memory 316, applications 375, buses 344, RF front end388, LNAs 390, switches 392, filters 396, PAs 398, and one or moreantennas 365 may be the same as or similar to the correspondingcomponents of UE 110, as described above, but configured or otherwiseprogrammed for base station operations as opposed to UE operations.

The PHR for SRS component 170 can include multiple subcomponents. Forexample, the PHR for SRS component 170 can include a PHR processor 171that receives and processes a PHR including first power information 172and second power information 174. The first power information 172includes a nominal power headroom value 173, such as PH⁽¹⁾ as describedabove. The second power information 174 includes additional powerheadroom values, such as PH⁽²⁾, . . . , PH^((x+1)), where X is thenumber of SRS ports in the UE 110. The information in the second powerinformation 174 (e.g., the power headroom values) can indicate thedesired transmit power 175 for the SRS ports, which is different fromthe actual transmit power 176 for the SRS ports. The desired transmitpower 155 can be provided in the form of absolute transmit power values(e.g., P₁, . . . , P_(X)) and/or in the form of differential transmitpower values (e.g., PH⁽²⁾=P₁ and PH^((i+1))=P_(i)−PH^((i)), for i=2, 3,. . . , X). The PHR for SRS component 170 is therefore configured toidentify the desired transmit powers for the SRS ports from the secondpower information 174 in the received PHR.

The PHR for SRS component 170 can also include a PHR type 177 thatidentifies a type of the PHR from the Type 1 PHR and the Type 2 PHR. ThePHR type indication 178 can also be included in the PHR for SRScomponent 170 and can be used to receive and process an indication ofthe PHR type.

Referring to FIG. 4, for example, a method 400 for wirelesscommunications in operating the UE 110 according to the above-describedaspects to provide enhanced PHR for feeding back beamformed SRS powerscaling includes one or more of the herein-defined actions.

For example, at 402, the method 400 includes generating, at a UE, a PHRincluding first power information (e.g., PH⁽¹⁾) indicating a nominalpower headroom value and second power information indicating a desiredtransmit power for each of multiple SRS ports of the UE (e.g., PH⁽²⁾, .. . , PH^((X))), where the desired transmit power for one or more of theSRS ports is different from a same transmit power used for an uplinktransmission on the SRS ports. For instance, in an aspect, the UE 110may execute the processor 212, the modem 140, and/or one or moresubcomponents of the PHR for SRS component 150, to generate the PHRhaving the first power information and the second power information.

At 404, the method 400 includes transmitting, by the UE, the PHR to abase station. For instance, in an aspect, the UE 110 may execute theprocessor 212, the modem 140, one or more subcomponents of the PHR forSRS component 150, the transceiver 202, and/or the RF front end 288 totransmit the PHR to the base station 105, as described herein.

In another aspect, the method 400 may optionally include, at 406,determining the desired transmit power for each of the SRS ports basedat least in part on scaling or power normalization factors. Thesefactors can depend on a noise covariance interference matrix that the UEobserves.

In another aspect, the method 400 may optionally include, at 408,determining the nominal power headroom value as a difference between amaximum transmit power (e.g., P_(CMax)) and a transmit power calculatedby the UE for a PUSCH (e.g., P_(PUSCHcalculated)).

In another aspect of the method 400, the second power informationindicates the desired transmit power for each of the SRS ports persubband.

In another aspect, the method 400 may optionally include, at 410,configuring the nominal power headroom value in accordance with a powerheadroom reporting format, and configuring the desired transmit powerfor each of the SRS ports is configured in accordance with the samepower headroom reporting format. For example, PH⁽¹⁾ can be configuredusing an 8-bit format and each of PH⁽²⁾, . . . , PH^((X+1)) (when the UEhas X ports) can also be configured using an 8-bit format. It is to beunderstood that if formats using more or fewer than 8-bit are possible,then the nominal power headroom value and the desired transmit powerscan all use such a format.

In another aspect of the method 400, the second power information caninclude a power headroom value for each of the SRS ports, where eachpower headroom value is indicative of an absolute value of thecorresponding desired transmit power (e.g., PH⁽²⁾=P₁, . . . ,PH^((X+1))=P_(X)).

In another aspect of the method 400, the second power information caninclude a power headroom value for each of the SRS ports, the powerheadroom value of a first SRS port being indicative of an absolute valueof the desired transmit power of the first SRS port (e.g., PH⁽²⁾=P₁),and the power headroom value of any remaining SRS port being indicativeof a difference in the desired transmit power between the SRS port and aprevious SRS port (e.g., PH^((i+1))=P_(i)−PH^((i)), where i=2, 3, . . ., X). At least one of the power headroom values for the SRS ports can beconfigured to use a power headroom reporting format with fewer bits thana power headroom reporting format used for the nominal power headroomvalue. That is, because what is being reported is a difference value,fewer bit may be needed to represent the difference value compared to anumber of bits needed to represent an absolute value.

In another aspect of the method 400, the second power informationincludes a power headroom value for each of the SRS ports, the powerheadroom value of a first SRS port being indicative of an absolute valueof the desired transmit power of the first SRS port (e.g., PH⁽²⁾=P₁),and the power headroom value of any remaining SRS port being indicativeof a difference in the desired transmit power between the SRS port andthe first SRS port (e.g., PH^((i+1))=P_(i)−PH⁽²⁾, where i=2, 3, . . . ,X). While the first SRS port is being used as a reference SRS port inthis example, a different SRS port can be used. At least one of thepower headroom values for the SRS ports can be configured to use a powerheadroom reporting format with fewer bits than a power headroomreporting format used for the nominal power headroom value.

In another aspect of the method 400, the PHR is a Type 2 PHR associatedwith DL-oriented SRS resources configured to support DLchannel-dependent scheduling and link adaptation. The Type 2 PHR isdifferent from a Type 1 PHR associated with UL-oriented SRS resourcesconfigured to support UL channel-dependent scheduling and linkadaptation. In yet another aspect, the UE can generate an indicationthat the UE is to change from using the Type 2 PHR to the Type 1 PHR,and can transmit the indication to the base station. Such indication canbe a single-bit indication.

In another aspect, the method 400 may optionally include, at 412,transmitting on the UL transmission using the same transmit power on theSRS ports.

Referring to FIG. 5, for example, a method 500 for wirelesscommunications in operating base station 105 according to theabove-described aspects to receive and process enhanced PHR for feedingback beamformed SRS power scaling includes one or more of theherein-defined actions.

For example, at 502, the method 500 includes receiving, at a basestation and from a UE, a PHR including first power informationindicating a nominal power headroom value and second power information.For instance, in an aspect, the base station 105 may execute theprocessor 312, the modem 160, one or more of the subcomponents of thePHR for SRS component 170, the transceiver 302, and/or the RF front end388 to receive the PHR, as described herein.

At 504, the method 500 includes identifying, from the second powerinformation, a desired transmit power for each of multiple SRS ports ofthe UE, where the desired transmit power for one or more of the SRSports is different from a same transmit power used for an ULtransmission on the SRS ports. For instance, in an aspect, the basestation 105 may execute the processor 312, the modem 160, and/or one ormore of the subcomponents of the PHR for SRS component 170 to identifyand process the desired transmit powers, as described herein.

In some aspects, the base station 105 may execute the processor 312, themodem 160, and/or one or more of the subcomponents of the PHR for SRScomponent 170 to configure the SRS ports as part of an SRS resourceconfiguration. In this example, the transmit power is configured for theSRS resource, and then using the PHR report, each port of the SRSresource may be transmitted with a desired power which is different foreach port.

In some aspects, may execute the processor 312, the modem 160, and/orone or more of the subcomponents of the PHR for SRS component 170 toconfigure a set of SRS resources using the same transmit power, whereall the SRS ports of each SRS resource of the set of SRS resources istransmitted using the desired transmit powers. In this example, thedesired transmit power of the SRS ports may be different from the sametransmit power of each of the SRS resources within the set of SRSresources.

In another aspect of the method 500, the desired transmit power for eachof the SRS ports is based at least in part on scaling normalizationfactors. For example, as described above, the power or scalingnormalization factors can depend on a noise covariance interferencematrix that the UE 110 observes.

In another aspect of the method 500, the UL transmission uses the sametransmit power in each of the SRS ports.

In another aspect of the method 500, the nominal power headroom value(e.g., PH⁽¹⁾) is a difference between a maximum transmit power and atransmit power calculated by the UE for a PUSCH.

In some implementations, the method 500, at 506, optionally includesprocessing the nominal power headroom value in accordance with a powerheadroom reporting format, and processing the desired transmit power foreach of the SRS ports in accordance with the same power headroomreporting format. The power headroom reporting format can be based on an8-bit format. It is to be understood that power headroom reportingformats with more or fewer bits can also be used.

In another aspect of the method 500, the second power information caninclude a power headroom value for each of the SRS ports, each powerheadroom value being indicative of an absolute value of thecorresponding desired transmit power.

In another aspect of the method 500, the second power information caninclude a power headroom value for each of the SRS ports, the powerheadroom value of a first SRS port being indicative of an absolute valueof the desired transmit power of the first SRS port, and the powerheadroom value of any remaining SRS port being indicative of adifference in the desired transmit power between the SRS port and aprevious SRS port. At least one of the power headroom values for the SRSports is configured to use a power headroom reporting format with fewerbits than a power headroom reporting format used for the nominal powerheadroom value.

In another aspect of the method 500, the second power information caninclude a power headroom value for each of the SRS ports, the powerheadroom value of a first SRS port being indicative of an absolute valueof the desired transmit power of the first SRS port, and the powerheadroom value of any remaining SRS port being indicative of adifference in the desired transmit power between the SRS port and thefirst SRS port. At least one of the power headroom values for the SRSports is configured to use a power headroom reporting format with fewerbits than a power headroom reporting format used for the nominal powerheadroom value.

In another aspect of the method 500, the PHR can be a Type 2 PHRassociated with DL-oriented SRS resources configured to support DLchannel-dependent scheduling and link adaptation. The Type 2 PHR isdifferent from a Type 1 PHR associated with UL-oriented SRS resourcesconfigured to support UL channel-dependent scheduling and linkadaptation.

In some implementations, the method 500, at 508 includes receiving, bythe base station, an indication that the UE is to change from using aType 2 PHR to a Type 1 PHR. The indication can be a single-bitindication.

In another aspect, the identifying the desired transmit power for eachof the SRS ports of the method 500 may optionally include, at 510,identifying the desired transmit power for each of the SRS ports persubband.

Although the operations or methods described above are presented in aparticular order and/or as being performed by an example component, itshould be understood that the ordering of the actions and the componentsperforming the actions may be varied, depending on the implementation.In addition, aspects of any one of the methods described above can becombined with aspects of any other of the methods.

The present disclosure also includes apparatuses having components orconfigured to execute or means for executing the above-describedmethods, and computer-readable mediums storing one or more codesexecutable by a processor to perform the above-described methods.

In an implementation, an apparatus, such as the UE 110, may includemeans for generating a power headroom report including first powerinformation indicating a nominal power headroom value and second powerinformation indicating a desired transmit power for each of multiplesounding reference signal (SRS) ports of the UE, wherein the desiredtransmit power for one or more of the SRS ports is different from a sametransmit power used for an uplink transmission on the SRS ports; andmeans for transmitting, by the UE, the power headroom report to a basestation.

In another implementation, an apparatus, such as the base station 105,may include means for receiving, from a UE, a power headroom reportincluding a first power information indicating a nominal power headroomvalue and a second power information; and means for identifying, fromthe second power information, a desired transmit power for each ofmultiple sounding reference signal (SRS) ports of the UE, wherein thedesired transmit power for one or more of the SRS ports is differentfrom a same transmit power used for an uplink transmission on the SRSports.

In another implementation, a computer-readable medium storing computercode executable by a processor for a UE, such as the UE 110, may includecode for generating a power headroom report including a first powerinformation indicating a nominal power headroom value and a second powerinformation indicating a desired transmit power for each of multiplesounding reference signal (SRS) ports of the UE, wherein the desiredtransmit power for one or more of the SRS ports is different from a sametransmit power used for an uplink transmission on the SRS ports; andcode for transmitting, by the UE, the power headroom report to a basestation.

In another implementation, a computer-readable medium storing computercode executable by a processor for a base station, such as the basestation 105, may include code for receiving, at a base station and froma UE, a power headroom report including a first power informationindicating a nominal power headroom value and a second powerinformation; and code for identifying, from the second powerinformation, a desired transmit power for each of multiple soundingreference signal (SRS) ports of the UE, wherein the desired transmitpower for one or more of the SRS ports is different from a same transmitpower used for an uplink transmission on the SRS ports.

The above detailed description set forth above in connection with theappended drawings describes examples and does not represent the onlyexamples that may be implemented or that are within the scope of theclaims. The term “example,” when used in this description, means“serving as an example, instance, or illustration,” and not “preferred”or “advantageous over other examples.” The detailed description includesspecific details for the purpose of providing an understanding of thedescribed techniques. These techniques, however, may be practicedwithout these specific details. In some instances, well-known structuresand apparatuses are shown in block diagram form in order to avoidobscuring the concepts of the described examples.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, computer-executable code or instructionsstored on a computer-readable medium, or any combination thereof.

The various illustrative blocks and components described in connectionwith the disclosure herein may be implemented or performed with aspecially-programmed device, such as but not limited to a processor, adigital signal processor (DSP), an ASIC, a FPGA or other programmablelogic device, a discrete gate or transistor logic, a discrete hardwarecomponent, or any combination thereof designed to perform the functionsdescribed herein. A specially-programmed processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aspecially-programmed processor may also be implemented as a combinationof computing devices, e.g., a combination of a DSP and a microprocessor,multiple microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on anon-transitory computer-readable medium. Other examples andimplementations are within the scope and spirit of the disclosure andappended claims. For example, due to the nature of software, functionsdescribed above can be implemented using software executed by aspecially programmed processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items prefaced by “at least one of” indicates a disjunctivelist such that, for example, a list of “at least one of A, B, or C”means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation,computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the common principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Furthermore, although elements of the describedaspects and/or embodiments may be described or claimed in the singular,the plural is contemplated unless limitation to the singular isexplicitly stated. Additionally, all or a portion of any aspect and/orembodiment may be utilized with all or a portion of any other aspectand/or embodiment, unless stated otherwise. Thus, the disclosure is notto be limited to the examples and designs described herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method for wireless communications, comprising:generating, by a user equipment (UE), a power headroom report includingfirst power information indicating a nominal power headroom value andsecond power information indicating a desired transmit power for each ofmultiple sounding reference signal (SRS) ports of the UE, wherein thedesired transmit power for one or more of the SRS ports is differentfrom a same transmit power used for an uplink transmission on the SRSports; and transmitting, by the UE, the power headroom report to a basestation.
 2. The method of claim 1, further comprising determining thedesired transmit power for each of the SRS ports based at least in parton scaling normalization factors.
 3. The method of claim 1, furthercomprising transmitting on the uplink transmission using the sametransmit power on the SRS ports.
 4. The method of claim 1, furthercomprising determining the nominal power headroom value as a differencebetween a maximum transmit power and a transmit power calculated by theUE for a physical uplink shared channel (PUSCH).
 5. The method of claim1, wherein the second power information indicates the desired transmitpower for each of the SRS ports per subband.
 6. The method of claim 1,wherein generating the power headroom report further comprises:configuring the nominal power headroom value in accordance with a powerheadroom reporting format, and configuring the desired transmit powerfor each of the SRS ports in accordance with the power headroomreporting format.
 7. The method of claim 1, wherein the second powerinformation includes power headroom values for the SRS ports, each ofthe power headroom values having a corresponding SRS port of the SRSports, each of the power headroom values being indicative of an absolutevalue of the corresponding desired transmit power.
 8. The method ofclaim 1, wherein the second power information includes power headroomvalues for the SRS ports, each of the power headroom values having acorresponding SRS port of the SRS ports, a power headroom value of afirst SRS port being indicative of an absolute value of the desiredtransmit power of the first SRS port, and a power headroom value of anyremaining SRS port being indicative of a difference in the desiredtransmit power between the SRS port and a previous SRS port.
 9. Themethod of claim 8, wherein at least one of the power headroom values forthe SRS ports is configured to use a power headroom reporting formatwith fewer bits than a power headroom reporting format used for thenominal power headroom value.
 10. The method of claim 1, wherein thesecond power information includes power headroom values for the SRSports, each of the power headroom values having a corresponding SRS portof the SRS ports, a power headroom value of a first SRS port beingindicative of an absolute value of the desired transmit power of thefirst SRS port, and a power headroom value of any remaining SRS portbeing indicative of a difference in the desired transmit power betweenthe SRS port and the first SRS port.
 11. The method of claim 10, whereinat least one of the power headroom values for the SRS ports isconfigured to use a power headroom reporting format with fewer bits thana power headroom reporting format used for the nominal power headroomvalue.
 12. The method of claim 1, wherein the power headroom report is aType 2 power headroom report (Type 2 PHR) associated withdownlink-oriented SRS resources configured to support downlinkchannel-dependent scheduling and link adaptation.
 13. The method ofclaim 12, wherein the Type 2 PHR is different from a Type 1 PHRassociated with uplink-oriented SRS resources configured to supportuplink channel-dependent scheduling and link adaptation.
 14. The methodof claim 13, further comprising: generating an indication that the UE isto change from using the Type 2 PHR to the Type 1 PHR; and transmittingthe indication to the base station.
 15. A method for wirelesscommunications, comprising: receiving, at a base station and from a userequipment (UE), a power headroom report including a first powerinformation indicating a nominal power headroom value and a second powerinformation; and identifying, from the second power information, adesired transmit power for each of multiple sounding reference signal(SRS) ports of the UE, wherein the desired transmit power for one ormore of the SRS ports is different from a same transmit power used foran uplink transmission on the SRS ports.
 16. The method of claim 15,wherein the desired transmit power for each of the SRS ports based atleast in part on scaling normalization factors.
 17. The method of claim15, wherein the uplink transmission uses a same transmit power in eachof the SRS ports.
 18. The method of claim 15, wherein the nominal powerheadroom value is a difference between a maximum transmit power and atransmit power calculated by the UE for a physical uplink shared channel(PUSCH).
 19. The method of claim 15, wherein identifying the desiredtransmit power for each of the SRS ports includes identifying thedesired transmit power for each of the SRS ports per subband.
 20. Themethod of claim 15, further comprising: processing the nominal powerheadroom value in accordance with a power headroom reporting format; andprocessing the desired transmit power for each of the SRS ports inaccordance with the power headroom reporting format.
 21. The method ofclaim 15, wherein the second power information includes power headroomvalues for the SRS ports, each of the power headroom values having acorresponding SRS port of the SRS ports, each power headroom value beingindicative of an absolute value of the corresponding desired transmitpower.
 22. The method of claim 15, wherein the second power informationincludes power headroom values for the SRS ports, each of the powerheadroom values having a corresponding SRS port of the SRS ports, apower headroom value of a first SRS port being indicative of an absolutevalue of the desired transmit power of the first SRS port, and a powerheadroom value of any remaining SRS port being indicative of adifference in the desired transmit power between the SRS port and aprevious SRS port.
 23. The method of claim 22, wherein at least one ofthe power headroom values for the SRS ports is configured to use a powerheadroom reporting format with fewer bits than a power headroomreporting format used for the nominal power headroom value.
 24. Themethod of claim 15, wherein the second power information includes powerheadroom values for the SRS ports, each of the power headroom valueshaving a corresponding SRS port of the SRS ports, a power headroom valueof a first SRS port being indicative of an absolute value of the desiredtransmit power of the first SRS port, and a power headroom value of anyremaining SRS port being indicative of a difference in the desiredtransmit power between the SRS port and the first SRS port.
 25. Themethod of claim 24, wherein at least one of the power headroom valuesfor the SRS ports is configured to use a power headroom reporting formatwith fewer bits than a power headroom reporting format used for thenominal power headroom value.
 26. The method of claim 15, wherein thepower headroom report is a Type 2 power headroom report (Type 2 PHR)associated with downlink-oriented SRS resources configured to supportdownlink channel-dependent scheduling and link adaptation.
 27. Themethod of claim 26, wherein the Type 2 PHR is different from a Type 1PHR associated with uplink-oriented SRS resources configured to supportuplink channel-dependent scheduling and link adaptation.
 28. The methodof claim 27, further comprising receiving an indication that the UE isto change from using the Type 2 PHR to the Type 1 PHR.
 29. An apparatusfor wireless communications, comprising: a memory storing instructions;and a processor in communication with the memory; wherein the processoris configured to execute the instructions to: generate, by a userequipment (UE), a power headroom report including first powerinformation indicating a nominal power headroom value and second powerinformation indicating a desired transmit power for each of multiplesounding reference signal (SRS) ports of the UE, wherein the desiredtransmit power for one or more of the SRS ports is different from a sametransmit power used for an uplink transmission on the SRS ports ; andtransmit, by the UE, the power headroom report to a base station.
 30. Anapparatus for wireless communications, comprising: a memory storinginstructions; and a processor in communication with the memory; whereinthe processor is configured to execute the instructions to: receive, ata base station and from a user equipment (UE), a power headroom reportincluding first power information indicating a nominal power headroomvalue and second power information; and identify, from the second powerinformation, a desired transmit power for each of multiple soundingreference signal (SRS) ports of the UE, wherein the desired transmitpower for one or more of the SRS ports is different from a same transmitpower used for an uplink transmission on the SRS ports.